Yan, Zheng e30b5dca15 ext4: fix fio regression ... We (Linux Kernel Performance project) found a regression introduced by commit: f7fec032aa ext4: track all extent status in extent status tree The commit causes about 20% performance decrease in fio random write test. Profiler shows that rb_next() uses a lot of CPU time. The call stack is: rb_next ext4_es_find_delayed_extent ext4_map_blocks _ext4_get_block ext4_get_block_write __blockdev_direct_IO ext4_direct_IO generic_file_direct_write __generic_file_aio_write ext4_file_write aio_rw_vect_retry aio_run_iocb do_io_submit sys_io_submit system_call_fastpath io_submit td_io_getevents io_u_queued_complete thread_main main __libc_start_main The cause is that ext4_es_find_delayed_extent() doesn't have an upper bound, it keeps searching until a delayed extent is found. When there are a lots of non-delayed entries in the extent state tree, ext4_es_find_delayed_extent() may uses a lot of CPU time. Reported-by: LKP project <lkp@linux.intel.com> Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com> Signed-off-by: Zheng Liu <wenqing.lz@taobao.com> Cc: "Theodore Ts'o" <tytso@mit.edu>		2013-05-03 02:15:52 -04:00
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acpi	Fixes:	2013-03-12 20:25:53 -07:00
asm-generic	asm-generic: move cmpxchg*_local defs to cmpxchg.h	2013-03-13 06:11:05 +01:00
clocksource	ImgTec Meta architecture changes for v3.9-rc1	2013-03-03 12:06:09 -08:00
crypto
drm	drm/radeon: add Richland pci ids	2013-03-15 18:47:19 -04:00
keys
linux	buffer: add BH_Prio and BH_Meta flags	2013-04-20 19:58:37 -04:00
math-emu
media	[media] media: ov7670: Add possibility to disable pixclk during hblank	2013-02-08 14:35:06 -02:00
memory
misc
net	ipv4: Fix ip-header identification for gso packets.	2013-03-26 13:50:05 -04:00
pcmcia
ras	edac: add support for error type "Info"	2013-02-21 14:16:27 -03:00
rdma	IB/core: Add "type 2" memory windows support	2013-02-21 11:51:45 -08:00
rxrpc
scsi	SCSI for-linus on 20130301	2013-03-02 11:42:16 -08:00
sound	arm-soc: late OMAP changes	2013-02-28 20:00:40 -08:00
target	target: Rename spc_get_write_same_sectors -> sbc_get_write_same_sectors	2013-02-23 12:46:14 -08:00
trace	ext4: fix fio regression	2013-05-03 02:15:52 -04:00
uapi	net: fix *_DIAG_MAX constants	2013-03-21 12:36:33 -04:00
video	ARM: at91: fix LCD-wiring mode	2013-03-13 11:05:04 +01:00
xen	for-linus-20130331	2013-03-31 11:38:59 -07:00
Kbuild